This invention relates to an improved expansible drive shaft rotary tool system and more particularly to hydraulically actuated expansible multiple drive shafts and associated variably positioned tools mounted on the drive shafts. The invention is herein illustratively described by reference to the presently preferred embodiment thereof; however, it will be recognized that certain modifications and changes therein with respect to details may be made without departing from the essential features involved.
The drive shaft mechanism comprising the present invention is applicable for example to supporting and rotatively driving sets of rotary male and female creasing wheels used in forming the fold lines for corrugated board box panels and the like. Precise positioning and continued mutual registry of the cooperating sets of creasing wheels is therefore desirable together with the ability to quickly and easily change their positions for different job requirements. Numerous other tool positioning applications also exist in industry wherein the invention may be applied to advantage such as cutters, grinders and many others.
It is not new in the art to employ expansible drive shafts to maintain rotary tools in any of selected operating positions along a shaft. For example, Warren et al. U.S. Pat. No. 3,173,325 discloses one such proposal wherein the support shafts for the tools are hollow to accommodate hydraulic fluid variably pressurizable to control the degree of expansion of the shaft wall and thereby the holding force exerted on the surrounding tools. Floating bearings are necessary in that case due to endwise expansion of the shaft accompanying its lateral bulging or expansion to hold the tools.
Wyllie et al. U.S. Pat. No. 3,166,013 represents another patent disclosing an expansible shaft in this case for supporting a tubular printing cylinder or for varying the tension or driving force on a web of paper. In that example grooves or channels in the base cylinder surface closely surrounded by the expansion sleeve communicate fluid to the various areas within the sleeve to effect its expansion with the printing tube centered on the shaft in order to hold the printing tube in place when fluid pressure is increased within the grooves.
In addition hydraulically expansible mandrels pressurized by internal piston-cylinder units have been proposed heretofore as mounting supports for individual tools, examples being U.S. Pat. Nos. to Atherholt, Sr., 2,971,765; Better et al., 2,963,298; and Sturgis, 2,938,347.
An object of the present invention is to provide a quick-acting, compact, lightweight, and leak-proof hydraulically actuatable expansible shaft mechanism that can be made as long as desired and of any desired diameter, while requiring minimum volumetric space in its expansion chamber, pressure source cylinder and connecting passages.
Another and related objective is to provide such a mechanism substantially devoid of tool position shifting caused by shaft elongation when the shaft's pressure chamber is pressurized, yet which does not sacrifice expansion sleeve flexibility in achieving this result. Thus, support bearings for the shaft may be conventional (i.e., need not be of the "floating" type) to accommodate endwise shifts, and precise positioning of tool elements along the shaft, whether established manually or by automatic positioning mechanisms, will be maintained during shaft expansion to grip and lock such tool elements in place.
In addition it is an object of the invention to incorporate compact and effective hydraulic fluid take-up and make-up provisions in such a shaft mechanism that not only reduces the chance of exterior leakage of hydraulic fluid under the high internal pressures used (e.g., up to 3,000 psi, for example) but that also serves as a source of make-up fluid to replace fluid seeping past the primary seal associated with the hydraulic plunger pressurization device should any such exterior leakage occur. In addition such make-up device provides a means to accommodate changes in total hydraulic fluid volumetric containment requirements caused by substantial temperature variations expanding or contracting the incompressible hydraulic fluid.
A more specific object hereof is to devise such a shaft mechanism wherein maximum effective shaft diameter expansion may be achieved by pressurization within the expansion chamber of the shaft without causing attendant and commensurate lengthening of the shaft and without incurring problems of shaft eccentricity affecting axial alignment of the rotary tool elements mounted on the shaft.
Still another object is a shaft mechanism of the described type employing a combined pneumatic and hydraulic pressurization apparatus avoiding the usual problems with rotary high pressure seals that must contain the fluid against leakage at high rotational shaft speeds such as 500 rpm or more. With the improved mechanism all of the hydraulic system is contained with the rotary shaft.